CAT1021, CAT1022, CAT1023
Supervisory Circuits with EEPROM Serial 2k-bit I2C Manual Reset and Watchdog Timer
www. onsemi. com
Description
The CAT1021, CAT1022 and CAT1023 are complete memory and
supervisory solutions for microcontroller−based systems. A EEPROM
Serial 2k−bit I2C memory and a system power supervisor with
brown−out protection are integrated together in low power CMOS technology. Memory interface is via a 400 kHz I2C bus.
SOIC−8 CASE 751BD
TSSOP−8 CASE 948S
The CAT1021 and CAT1023 provide a precision VCC sense circuit
and two open drain outputs: one (RESET) drives high and the other
(RESET) drives low whenever VCC falls below the reset threshold
voltage. The CAT1022 has only a RESET output and does not have a Write Protect input. The CAT1021 also has a Write Protect input (WP). Write operations are disabled if WP is connected to a logic high.
MSOP−8 CASE 846AD
TDFN−8 CASE 511AL
All supervisors have a 1. 6 second watchdog timer circuit that resets
a system to a known state if software or a hardware glitch halts or
“hangs” the system. For the CAT1021 and CAT1022, the watchdog
ORDERING INFORMATION
timer monitors the SDA signal. The CAT1023 has a separate watchdog timer interrupt input pin, WDI.
For Ordering Information details, see page 13.
The power supply monitor and reset circuit protect memory and
system controllers during power up/down and against brownout
conditions. Five reset threshold voltages support 5 V, 3. 3 V and 3 V
systems. If power supply voltages are out of tolerance reset signals
become active, preventing the system microcontroller, ASIC or
peripherals from operating. Reset signals become inactive typically
200 ms after the supply voltage exceeds the reset threshold level. With
both active high and low reset signals, interface to microcontrollers
and other ICs is simple. In addition, the RESET pin or a separate input,
MR, can be used as an input for push−button manual reset capability.
The on−chip, 2k−bit EEPRO...
CAT1021 PDF File
